Sally Potter’s wacked historical suds opera is a showcase of future-resume embarrassments, from John Turturro flashing his guileless gawk-smile as a very, very famous Italian opera singer to Cate Blanchett, as a Moscow gold digger, preening like Mata Hari played by Gwen Stefani impersonating Veronica Lake. Christina Ricci, with her disaffected stare of ”Whatever!” blankness, looks like she’d rather be playing videogames.